FIG. 1 depicts a system level diagram of a television system 100. A typical configuration of the television system 100 comprises a signal source 110, a set top terminal 120 and a television receiver 130. The signal source 110 provides a television signal, e.g., a National Television Standard Committee (NTSC) television signal or a high definition television (HDTV) signal, for use in the television system 100. Examples of such video sources 110 may include an antenna for producing “over-the-air” television signals, a cable carrying cable television signals or a satellite receiver for generating satellite television signals.
The set top terminal 120 receives the television signal from the signal source 110. If the received television signal is RF or IF, the set top terminal 120 may convert the video and audio portions of the received television signal into baseband signals. The set top terminal 120 processes the video and audio components of the television signal into a suitable format, e.g., NTSC format, for display on the television receiver 130. Examples of set top terminals 120 may include a cable box, a video cassette recorder (VCR), or an Advanced Television Systems Committee (ATSC) legacy converter box.
The television receiver 130 processes the television signal, e.g., a NTSC signal, to display standard video and audio programmed content. Recent versions of the television receiver 130 may provide closed caption information pursuant to the Television Decoder Circuitry Act of 1990 and V-chip rating control pursuant to the Telecommunications Act of 1996. As such, the television receiver 130 may decode and display information embedded, e.g., line 21 information, in the television signal. In this case, the set top terminal 120 generally passes the television signal from the signal source 110 to the television receiver 130.
However, the set top terminal 120 is also capable of decoding and processing the television signal for display on the television receiver 130. This processing is normally performed where the television receiver 130 is a legacy television incapable of independently decoding embedded information in the television signal. In this case, only the set top terminal 120 may process embedded information used to provide closed captioning and filter video content.
A problem exists if both the set top terminal 120 and television receiver 130 decode and process the television signal for display. As the set top terminal 120 and television receiver may independently process embedded information for display, conflicts between the set top terminal 120 and television receiver 130 may arise. In one example, both the set top terminal 120 and television receiver 130 may provide separate closed caption displays over the displayed video. If the closed caption displays are not placed with identical positions and identical fonts from the set top terminal 120 and television receiver 130, then these closed caption displays will overlap, thereby creating a confusing display.
In another example, the set top terminal 120 and television receiver 130 perform block or pass program content based on V-chip information. For example, a set top terminal 120 may pass or allow program content that is then blocked by a downstream television receiver 130. Since only the display from the downstream television receiver 130, i.e., the device blocking the program, is shown, the viewer loses feedback from the tuning device, i.e., the set top terminal 120. Moreover, if the television system 100 comprises multiple set top terminals 120, e.g., a cable box and a VCR, it would be difficult to determine which set top terminal 120 is actually blocking the program content.
In another example, the set top terminal 120, e.g., a VCR, may record a program with a time index or timestamp typically embedded in line 21 of the television signal. As a downstream set top terminal 120 or television receiver 130 utilizes this timestamp to set a display clock. As such, when the television signal is played back at a later time, the playing device would provide erroneous time information.
Therefore, a need exists in the art for eliminating the display conflicts between the set top terminal and the television receiver.